Because digital controllers are becoming more complex, and are operating at ever-increasing speeds, the equipment for testing such controllers is also becoming more complex and more expensive. Developments in test equipment which provide lower costs and better testing techniques are, therefore, most useful.
Controllers are customarily tested after component assembly is completed in order to find and remove any defects. Whether they are related to manufacturing (such as solder shorts, copper shorts or wrong, misplaced or missing components), defective components, or errors in software installation, expected outputs in response to predetermined inputs are typically evaluated.
Instrument cluster controllers for gauge needles are customarily evaluated by probing the board at strategic testing locations and by optical observation of the gauge cluster. The cluster controllers can also be both stimulated and monitored through the probe points. In the past, it has frequently been necessary to verify needle movement manually or by using camera based verification systems. These systems are, however, costly and in the case of camera based systems, also can degrade the response signal to movement of the gauge, because of problems inherent in machine vision technologies. As such, the evaluation of these forms of control signals has been found in the past to be problematic and difficult. Development of techniques to automatically evaluate digital controller stepper motor signals would therefore be useful.